As it is well known to the public, a wide range of products, specially foods, such as fruits, vegetables and others are packed, in given quantity and weight, in plastic-film wrappings for sale in supermarkets and the like.
Said plastics wrappings are obtained from retractile or shrinkable thermoplastic films, that is, films which are applied to envelop such products and are capable of shrinking under the action of a heat source, so as to conform to the shape of the products to be packed. The resulting tightly-packed products form a single unit which renders them easier to handling, stocking or transportation.
In order to accomplish the formation of such plastics wrappings or "blisters" around the products, machine assemblies have been used in which two separate units, i.e., a sealing machine and a shrink tunnel are disposed one after the other according to their order in the operation line. In the sealing machine, a continuous longitudinally folded sheet of plastic film is fed from a reel onto a table where a sheet section is led to conform to the shape of the products to be packed, said sheet section enclosing the goods being then sealed and simultaneously cut off. The packed unit is then taken into a shrink tunnel where the shrinkage of the plastics film around the products is promoted by means of a heat source, thus ending the packaging operation.
Although this type of packaging machine assemblies is largely used at present, it has disadvantages in that it calls for the association of two separately constructed units thus envolving high installation and maintenance costs.
In order to overcome the disadvantages arising from the association of two independent machines, I have devised the improvements which are the object of the present invention.